Another example of how bridged taps can be misinter-
preted is shown below: In Figure 4, there appears to be
a
short
at Point B on the waveform. However, the
waveform shown in Figure 4 is actually the same wave-
form shown in Figure 5. The only difference is the
operator has used the zoom function to show only a
specific section of cable in Figure 4. The amount of
cable shown on the display is not enough to see the end
of the lateral or the end of the cable.
Figure 4
Figure 5
Remember, when testing with a TDR, always start the
test in the shortest pulse width or range possible. Con-
tinue to increase the pulse width or range until the entire
waveform has been viewed. This procedure will insure
that no faults are accidentally missed and waveforms
are not misinterpreted.